Question 337669
Rate*Time=Distance
.
.
.
{{{10*T1=X}}}
{{{T1=X/10}}}
.
.
.
{{{8*T2=X}}}
{{{T2=X/8}}}
.
.
.
Total distance = {{{2X}}}
Total time={{{T1+T2=X/10+X/8=(4/40)X+(5/40)X=(9/40)X}}}
Average speed=Total distance/Total time={{{2X/((9/40)X)=2*(40/9)=80/9}}}mph